scholarly journals Gas discrimination by simultaneous sound velocity and attenuation measurements using uncoated capacitive micromachined ultrasonic transducers

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Luis Iglesias Hernandez ◽  
Priyadarshini Shanmugam ◽  
Jean-François Michaud ◽  
Daniel Alquier ◽  
Dominique Certon ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Ultrasonic Transducers ◽  
Multiple Reflections ◽  
Nuclear Waste Storage ◽  
Capacitive Micromachined Ultrasonic Transducers ◽  
Long Term Stability ◽  
Waste Storage ◽  
Potential Applications ◽  
Hazardous Gases

AbstractChemically functionalized or coated sensors are by far the most employed solution in gas sensing. However, their poor long term stability represents a concern in applications dealing with hazardous gases. Uncoated sensors are durable but their selectivity is poor or non-existent. In this study, multi-parametric discrimination is used as an alternative to selectivity for uncoated capacitive micromachined ultrasonic transducers (CMUTs). This paper shows how measuring simultaneously the attenuation coefficient and the time of flight under different nitrogen mixtures allows to identify hydrogen, carbon dioxide and methane from each other and determine their concentration along with identification of temperature and humidity drifts. Theoretical comparison and specific signal processing to deal with the issue of multiple reflections are also presented. Some potential applications are monitoring of refueling stations, vehicles and nuclear waste storage facilities.

scholarly journals Gas Discrimination by Simultaneous Sound Velocity and Attenuation Measurements using Uncoated Capacitive Micromachined Ultrasonic Transducers

2021 ◽  
Author(s):  
Luis Iglesias Hernandez ◽  
Priyadarshini Shanmugam ◽  
Jean-Francois Michaud ◽  
Daniel Alquier ◽  
Dominique Certon ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Ultrasonic Transducers ◽  
Multiple Reflections ◽  
Temperature Drift ◽  
Nuclear Waste Storage ◽  
Capacitive Micromachined Ultrasonic Transducers ◽  
Long Term Stability ◽  
Waste Storage ◽  
Potential Applications ◽  
Hazardous Gases

Abstract Chemically functionalized or coated sensors are by far the most employed solution in gas sensing. However, their poor long term stability represents a concern in applications dealing with hazardous gases. Uncoated sensors are durable but their selectivity is poor or non-existent. In this study, multi-parametric discrimination is used as an alternative to selectivity for uncoated capacitive micromachined ultrasonic transducers (CMUTs). This paper shows how measuring simultaneously the attenuation coefficient and the time of flight under different nitrogen mixtures allows to identify hydrogen, carbon dioxide and methane from each other and determine their concentration along with identification of temperature drift. Theoretical comparison and specific signal processing to deal with the issue of multiple reflections are also presented. Some potential applications are monitoring of refueling stations, vehicles and nuclear waste storage facilities.

scholarly journals Improved Long‐Term Stability and Reduced Humidity Effect in Gas Sensing: SiO 2 Ultra‐Thin Layered ZnO Columnar Films

2021 ◽  
pp. 2001137
Author(s):  
Vasile Postica ◽  
Oleg Lupan ◽  
Anna Gapeeva ◽  
Luka Hansen ◽  
Rasoul Khaledialidusti ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Humidity Effect ◽  
Term Stability ◽  
Long Term Stability

scholarly journals Enhanced Methane Sensing Properties of WO3 Nanosheets with Dominant Exposed (200) Facet via Loading of SnO2 Nanoparticles

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 351 ◽  
Author(s):  
Dongping Xue ◽  
Junjun Wang ◽  
Yan Wang ◽  
Guang Sun ◽  
Jianliang Cao ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Defect Density ◽  
Sno2 Nanoparticles ◽  
High Reactivity ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
Sensing Properties ◽  
Long Term Stability ◽  
Subsequent Calcination

Methane detection is extremely difficult, especially at low temperatures, due to its high chemical stability. Here, WO3 nanosheets loaded with SnO2 nanoparticles with a particle size of about 2 nm were prepared by simple impregnation and subsequent calcination using SnO2 and WO3·H2O as precursors. The response of SnO2-loaded WO3 nanosheet composites to methane is about 1.4 times higher than that of pure WO3 at the low optimum operating temperature (90 °C). Satisfying repeatability and long-term stability are ensured. The dominant exposed (200) crystal plane of WO3 nanosheets has a good balance between easy oxygen chemisorption and high reactivity at the dangling bonds of W atoms, beneficial for gas-sensing properties. Moreover, the formation of a n–n type heterojunction at the SnO2-WO3 interface and additionally the increase of specific surface area and defect density via SnO2 loading enhance the response further. Therefore, the SnO2-WO3 composite is promising for the development of sensor devices to methane.

scholarly journals A Room Temperature Gas Sensor Based on Sulfonated SWCNTs for the Detection of NO and NO2

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1116 ◽  
Author(s):  
Eusebiu Ionete ◽  
Stefan Spiridon ◽  
Bogdan Monea ◽  
Elena Stratulat
Keyword(s):  
Room Temperature ◽  
Gas Sensing ◽  
Electrical Response ◽  
Long Term Stability ◽  
Sensing Applications ◽  
Specific Configuration ◽  
P Type ◽  
Walled Carbon Nanotubes ◽  
Type Response

The electrical response of sulfonated single-walled carbon nanotubes (SWCNTs) to NO and NO2, for gas sensing applications, at room temperature, is reported in this work. A specific configuration based on SWCNT deposition between double pair configuration gold electrodes, supported on a substrate, was considered for the sensing device; employed characterization technique where FTIR and SEM. The experimental results showed a p-type response of the sulfonated SWCNTs, with decrease in resistance, under exposure to NO gas (40–200 ppb) and NO2 (40–200 ppb). Also, the sensor responses to successive exposures at NO2 800 ppb together with investigation of long term stability, at 485 ppb for NO, are reported. The reaction mechanism in case of NO and NO2 detection with sulfonated SWCNTs is presented.

HOT WATER-REPELLENT SUPERHYDROPHOBIC SURFACES WITH LONG-TERM STABILITY

2021 ◽  
Author(s):  
JI SEONG CHOI ◽  
SEONG MIN KANG
Keyword(s):  
Hot Water ◽  
Superhydrophobic Surfaces ◽  
Water Repellent ◽  
Water Droplets ◽  
Long Term Stability ◽  
Cassie State ◽  
Potential Applications ◽  
Different Temperatures ◽  
Temperature Water

In this paper, we fabricate and evaluate superhydrophobic surfaces with mushroom-shaped microstructures. Using a silicon master and polymer microstructure patterning, polydimethylsiloxane (PDMS) surfaces bearing mushroom-shaped structures with five different spacing ratios are prepared and tested with water droplets of different temperatures. The fabricated PDMS surfaces demonstrate superhydrophobicity even to high-temperature water droplets with decreased surface tension. We compare the experimental data with the theoretical results calculated based on the Cassie state and Eötvös rule. Our work suggests potential applications to control wettability with liquids of various temperatures.

scholarly journals Ethylene detection in fruit supply chains

2014 ◽  
Vol 372 (2017) ◽  
pp. 20130311 ◽  
Author(s):  
S. Janssen ◽  
K. Schmitt ◽  
M. Blanke ◽  
M. L. Bauersfeld ◽  
J. Wöllenstein ◽  
...  
Keyword(s):  
Supply Chains ◽  
Mobile Application ◽  
Gas Sensing ◽  
Electrochemical Measurement ◽  
Measurement Systems ◽  
Long Term Stability ◽  
Sensing Systems ◽  
Cost Efficient

Ethylene is a gaseous ripening phytohormone of fruits and plants. Presently, ethylene is primarily measured with stationary equipment in laboratories. Applying in situ measurement at the point of natural ethylene generation has been hampered by the lack of portable units designed to detect ethylene at necessary resolutions of a few parts per billion. Moreover, high humidity inside controlled atmosphere stores or containers complicates the realization of gas sensing systems that are sufficiently sensitive, reliable, robust and cost efficient. In particular, three measurement principles have shown promising potential for fruit supply chains and were used to develop independent mobile devices: non-dispersive infrared spectroscopy, miniaturized gas chromatography and electrochemical measurement. In this paper, the measurement systems for ethylene are compared with regard to the needs in fruit logistics; i.e. sensitivity, selectivity, long-term stability, facilitation of automated measurement and suitability for mobile application. Resolutions of 20–10 ppb can be achieved in mobile applications with state-of-the-art equipment, operating with the three methods described in the following. The prices of these systems are in a range below €10 000.

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